Converter control circuit and conversion system

Abstract

The invention relates to the technical field of power supplies, and mainly provides a converter control circuit and a conversion system, and the circuit comprises a sampling resistor, and a driving module and a triggering module which are connected with the sampling resistor. The sampling resistor is used for outputting sampling voltage according to the change of inductive current in the converter; the trigger module is used for outputting a trigger signal to the controller at the moment that the sampling voltage is greater than the preset voltage, so that the controller controls a power tube in the converter to act; the driving module is used for controlling a freewheeling tube in the converter to be switched on when the pulse signal is the first level and the sampling voltage is greater than the preset voltage; and when the sampling voltage is smaller than the preset voltage or the pulse signal is the second level, the freewheeling tube is controlled to be turned off. On the basis, the action time of the power tube and the follow current tube can be determined in real time according to the inductive current, so that the corresponding currents during the action of the two tubes are consistent, and the action time of the two tubes is adjusted in real time according to the relationship between the load condition of the converter and the inductive current, so that the loss of the power tube is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of power supplies, and in particular to a converter control circuit and a conversion system. Background Art

[0002] Buck / Boost converter circuit topology has the advantages of simple structure, low cost, easy control and high reliability. It is widely used in photovoltaic power generation, hybrid vehicles and energy storage systems, and has become the most commonly used topology for non-isolated DC / DC buck converters. In engineering applications, in order to effectively reduce the switching loss and electromagnetic radiation interference of the switch tube while increasing the switching frequency, soft switching technology has come into being. In order to reduce the complexity of traditional soft switching technology, sampling TCM control is mostly used to achieve the soft switching action of the switch tube. Among them, TCM control refers to the use of inductor current to achieve the soft switching action of the switch tube.

[0003] However, the magnitude of the converter inductor current is determined by the load state of the converter, so the time for the terminal voltage of the parasitic capacitance of the switch tube to resonate to zero is also different. In the actual setting, the dead zone voltage of the switch tube is set according to the light load of the converter, which results in that when the converter is heavily loaded, the inductor current will resonate the terminal voltage of the parasitic capacitance of the switch tube to zero in a very short time, making the anti-parallel diode in the switch tube body conduct for a long time, and this working state increases the conduction loss of the converter to a certain extent, thereby reducing the conversion efficiency of the converter. In addition, due to the differences between devices, there is an error between the calculated dead time and the actual required dead time, which results in the inductor current value when the converter's freewheeling tube is turned off and the inductor current value when the power tube is turned on are not equal, thereby affecting the stability and safety of the converter. Summary of the invention

[0004] The embodiments of the present invention provide a converter control circuit and a conversion system, which mainly solve the technical problems of large switching loss, low conversion efficiency and low stability of the converter in the prior art.

[0005] In order to solve the above technical problems, a technical solution adopted in the embodiment of the present invention is: providing a converter control circuit, the converter control circuit comprising a sampling resistor, a driving module and a trigger module; The sampling resistor is connected to the driving module and the triggering module respectively, the sampling resistor is also used to connect the converter, the triggering module is also connected to the controller, the driving module is also used to connect the freewheeling tube in the converter, and the driving module is also used to receive the pulse signal; The sampling resistor responds to the change of the inductor current in the converter and outputs a corresponding sampling voltage based on the changed inductor current; The trigger module is used to receive the sampled voltage and output a trigger signal to the controller at the moment when the sampled voltage is greater than a preset voltage, so that the controller controls the action of the power tube in the converter according to the trigger signal; The driving module is used to receive the sampled voltage, and when the pulse signal is at a first level, determine whether the sampled voltage is greater than the preset voltage, so as to output an opening signal to the freewheeling tube in the converter when the sampled voltage is greater than the preset voltage, thereby controlling the freewheeling tube in the converter to be opened according to the opening signal; and When the sampling voltage is less than the preset voltage or the pulse signal is at the second level, a shutdown signal is output to the converter, so that the freewheeling tube in the converter is shut down according to the shutdown signal.

[0006] Optionally, the trigger signal is the moment when the first signal jumps to the second signal, and the trigger module includes a first comparison unit and a trigger unit; The first comparison unit is connected to the trigger unit, the first comparison unit and the trigger unit are also connected to the sampling resistor, and the trigger unit is also connected to the controller; The first comparison unit is used to receive the sampled voltage, and output a first control signal to the trigger unit when the sampled voltage is less than the preset voltage, so that the trigger unit outputs a first signal to the controller according to the first control signal; and When the sampled voltage is greater than the preset voltage, a second control signal is output to the trigger unit, so that the trigger unit outputs a second signal to the controller according to the second control signal, thereby enabling the controller to control the action of the power tube in the converter.

[0007] Optionally, the first comparison unit includes a comparator U2, a resistor R15, a resistor R17, a capacitor C10 and a capacitor C11; The non-inverting input terminal of the comparator U2 is connected to the sampling resistor through the resistor R17, the non-inverting input terminal of the comparator U2 is also grounded through the capacitor C10, the inverting input terminal of the comparator U2 is connected to the reference power supply through the resistor R15, the inverting input terminal of the comparator U2 is also grounded through the capacitor C11, and the output terminal of the comparator U2 is connected to the trigger unit.

[0008] Optionally, the trigger unit includes a resistor R19, a resistor R20, a resistor R13, a resistor R18, a switch tube Q5, a comparator U3, a capacitor C7 and a capacitor C8; The control end of the switch tube Q5 is connected to the first comparison unit through the resistor R19, and the control end of the switch tube Q5 is also grounded through the resistor R20. The first end of the switch tube Q5 is connected to the non-inverting input end of the comparator U3, and the non-inverting input end of the comparator U3 is also connected to the reference power supply through the resistor R13. The non-inverting input end of the comparator U3 is also grounded through the capacitor C8. The inverting input end of the comparator U3 is connected to the sampling resistor through the resistor R18, and the inverting input end of the comparator U3 is also grounded through the capacitor C7. The output end of the comparator U3 is connected to the controller.

[0009] Optionally, the driving module includes a first control unit, a second comparison unit and a second control unit; The second comparison unit is connected to the first control unit and the second control unit respectively, the second comparison unit is also connected to the sampling resistor, the second control unit is also connected to the freewheeling tube in the converter, and the first control unit is also used to receive the pulse signal; The first control unit is used to control the second comparison unit to determine whether the sampling voltage is greater than a preset voltage when the pulse signal is at a first level, so that the second comparison unit outputs a first drive signal to the second control unit when the sampling voltage is greater than the preset voltage; and outputs a second drive signal to the second control unit when the sampling voltage is less than the preset voltage; and When the pulse signal is at a second level, controlling the second comparing unit to output a second driving signal to the second controlling unit; The second control unit is used for outputting an opening signal to the freewheeling tube in the converter when receiving the first driving signal, so that the freewheeling tube in the converter is opened according to the opening signal; and When the second driving signal is received, a shutdown signal is output to the converter, so that the freewheeling tube in the converter is turned off according to the shutdown signal.

[0010] Optionally, the second comparison unit includes a comparator U4, a resistor R23 and a capacitor C14; The non-inverting input terminal of the comparator U4 is connected to the sampling resistor and the first control unit respectively, the inverting input terminal of the comparator U4 is connected to the reference power supply through the resistor R23, the inverting input terminal of the comparator U4 is also grounded through the capacitor C14, and the output terminal of the comparator U4 is connected to the second control unit.

[0011] Optionally, the driving module further includes a delay unit; The delay unit is connected to the sampling resistor and the second comparison unit respectively; The delay unit is used to obtain the sampled voltage, and based on the magnitude of the sampled voltage, delay the sampled voltage by a corresponding time and then input it into the second comparison unit.

[0012] Optionally, the second control unit includes a resistor R29, a resistor R30, a resistor R31, a resistor R32, a switch tube Q7, a switch tube Q8, a switch tube Q9 and a switch tube Q10; The control end of the switch tube Q7 is connected to the second comparison unit, the first end of the switch tube Q7 is connected to the control end of the switch tube Q8 through the resistor R30, the control end of the switch tube Q8 is also connected to the first power supply through the resistor R29, the second end of the switch tube Q8 is respectively connected to the control ends of the switch tube Q9 and the switch tube Q10 through the resistor R31, the control end of the switch tube Q10 is also grounded through the resistor R32, the first end of the switch tube Q8 and the first end of the switch tube Q9 are both connected to the first power supply, and the second end of the switch tube Q9 and the first end of the switch tube Q10 are also both connected to the freewheeling tube in the converter.

[0013] Optionally, the converter control circuit further includes an amplification module; The amplification module is respectively connected to the sampling resistor, the trigger module and the driving module; The amplifying module is used for receiving the sampling voltage output by the sampling resistor, and amplifying the sampling voltage and then outputting it to the triggering module and the driving module.

[0014] In order to solve the above technical problems, another technical solution adopted in the embodiment of the present invention is: providing a conversion system, the conversion system comprising: Converter; Controller; and A converter control circuit as described above.

[0015] Different from the related art, the present invention provides a converter control circuit and a conversion system, the circuit comprising a sampling resistor, a driving module and a trigger module; the sampling resistor is connected to the driving module and the trigger module respectively, the sampling resistor is also used to connect the converter, the trigger module is also connected to the controller, the driving module is also used to connect the freewheeling tube in the converter, and the driving module is also used to receive a pulse signal; the sampling resistor responds to the change of the inductor current in the converter, and outputs a corresponding sampling voltage based on the changed inductor current; the trigger module is used to receive the sampling voltage, and output a corresponding sampling voltage at the moment when the sampling voltage is greater than a preset voltage. The drive module is used to receive the sampling voltage and determine whether the sampling voltage is greater than the preset voltage when the pulse signal is at the first level, so as to output an on signal to the freewheeling tube in the converter when the sampling voltage is greater than the preset voltage, thereby controlling the freewheeling tube in the converter to be turned on according to the on signal; and when the sampling voltage is less than the preset voltage or the pulse signal is at the second level, output a shutoff signal to the converter, so that the freewheeling tube in the converter is turned off according to the shutoff signal. Based on this, the action time of the power tube and the freewheeling tube can be determined in real time according to the inductor current, so that the current corresponding to the freewheeling tube and the power tube when they are in action is consistent, thereby improving the stability and safety of the converter; and the action time of the power tube and the freewheeling tube can be adjusted in real time according to the relationship between the load condition of the converter and the inductor current, thereby reducing the loss of the power tube and improving the conversion efficiency of the converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] One or more embodiments are exemplarily described by corresponding drawings, which do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and the figures in the drawings do not constitute proportional limitations unless otherwise stated.

[0017] Figure 1 is a structural block diagram of a conversion system provided by an embodiment of the present invention; Figure 2a is a circuit diagram of a Buck converter provided by an embodiment of the present invention; Figure 2b is a circuit diagram of a Boost converter provided by an embodiment of the present invention; Figure 3 is a waveform diagram of a converter operation provided by an embodiment of the present invention; Figure 4 is a structural block diagram of a converter control circuit provided by an embodiment of the present invention; Figure 5Detailed description of the invention The invention relates to a circuit diagram of a converter control circuit. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0019] It should be noted that, if there is no conflict, the various features in the embodiments of the present invention can be combined with each other, and all are within the protection scope of the present invention. In addition, although the functional modules are divided in the device schematic diagram and the logical order is shown in the flow chart, in some cases, the steps shown or described can be performed in a different order from the module division in the device schematic diagram or the order in the flow chart.

[0020] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0021] See also Figure 1 , Figure 1 is a structural block diagram of a conversion system provided by an embodiment of the present invention, such as Figure 1 As shown, the conversion system 100 includes a converter 10, a controller 20 and a converter control circuit 30; the converter control circuit 30 is connected to the converter 10 and the controller 20 respectively. The converter control circuit 30 is used to detect the output current of the converter 10, and output a corresponding trigger signal to the controller 20 based on the change of the output current, so that the controller 20 controls the on and off of the switch tube in the converter 10 based on the trigger signal. The converter 10 can be a Buck converter or a Boost converter.

[0022] For further information, please refer to the Buck converter. Figure 2a , Figure 2a is a circuit diagram of a Buck converter provided by an embodiment of the present invention, such as Figure 2a As shown, the converter 10 includes a switch tube Q1 (power tube), a switch tube Q2 (freewheeling tube), a resonant inductor Lr and a capacitor C2. The switch tube Q1 and the switch tube Q2 are connected in series, the second end of the switch tube Q1 is also connected to the capacitor C2 through the resonant inductor Lr, and the control ends of the switch tube Q1 and the switch tube Q2 are also connected to the controller 20.

[0023] It should be noted that, during the operation of the converter 10, the controller 20 is mainly used to control the on and off of the switch tube Q1 and the switch tube Q2 to change the input voltage (DC-IN+) of the converter 10, thereby outputting the target voltage. The switch tube Q1 and the switch tube Q2 both include parasitic capacitance. During the on and off process of the switch tube Q1 and the switch tube Q2, the parasitic capacitance will store voltage, which will cause the switch tube Q1 and the switch tube Q2 to have a large loss when they are turned off or turned on. Therefore, when realizing voltage conversion through the switch tube, it is necessary to ensure that the switch tube Q1 and the switch tube Q2 are in a soft switching state to reduce the loss of the switch tube, thereby increasing the service life of the converter 10. Specific, combined Figure 2a and Figure 3 , when there is input voltage and the switch tube Q1 is in the off state, and the switch tube Q2 is in the on state, the inductor current on the resonant inductor Lr will flow into the ground terminal through the switch tube Q2, and at this time the inductor current will decrease in the positive direction (that is, the inductor current continues to decrease). When the inductor current on the resonant inductor Lr decreases to 0, the capacitor C2 will reversely charge the resonant inductor Lr, thereby causing the inductor current to increase in the reverse direction (that is, the inductor current continues to decrease), and when the inductor current reversely increases to a preset value (I n-set ), the switch tube Q2 will be turned off. Since the inductor current starts to charge the parasitic capacitor of the switch tube Q2 only after the switch tube Q2 is turned off, the voltage stored in the parasitic capacitor is 0 when the switch tube Q2 is in operation, thereby achieving soft turn-off of the switch tube Q2.

[0024] When the switch tube Q2 is turned off, the resonant inductor Lr resonates with the parasitic capacitance of the switch tube Q1 and the parasitic capacitance of the switch tube Q2, so that the inductor current i of the resonant inductor Lr is Lr (t) continues to increase in the reverse direction, and the voltage u of the parasitic capacitance of the switch tube Q2 C2 (t) starts to increase positively, and the voltage u of the parasitic capacitance of the switch tube Q1 C1 (t) decreases in the positive direction. During the resonance process, the voltage on the parasitic capacitor of the switch tube Q2 increases in the positive direction to a maximum value (V pm ), the voltage on the parasitic capacitance of the switch tube Q1 also drops to the minimum value (-V F). When the voltage stored in the parasitic capacitor of the switch tube Q2 increases to a maximum value in the positive direction, the parasitic capacitor of the switch tube Q2 begins to discharge the resonant inductor Lr, so that the inductor current on the resonant inductor Lr begins to decrease in the reverse direction (that is, the inductor current increases slowly). Among them, when the voltage stored in the parasitic capacitor of the switch tube Q1 decreases to a certain value, the switch tube Q1 is turned on, thereby realizing the soft turn-on of the switch tube Q1.

[0025] When the switch tube Q1 is turned on, the input voltage will charge the resonant inductor Lr through the switch tube Q1. At this time, the inductor current of the resonant inductor Lr continues to decrease in the reverse direction. When the inductor current decreases to 0, the inductor current starts to increase in the positive direction until it increases to the maximum value I pm At this time, the switch tube Q1 is turned off, and because the voltage stored in the parasitic capacitor of the switch tube Q1 is 0, the switch tube Q1 is softly turned off.

[0026] When the switch tube Q1 is turned off, the resonant inductor Lr begins to resonate with the parasitic capacitance of the switch tube Q1 and the parasitic capacitance of the switch tube Q2, so that the voltage stored in the parasitic capacitance of the switch tube Q1 continues to increase, while the voltage stored in the parasitic capacitance of the switch tube Q2 continues to decrease, and the inductor current also continues to decrease. When the voltage stored in the parasitic capacitance of the switch tube Q2 is 0, the switch tube Q2 is turned on, thereby realizing the soft turn-on of the switch tube Q2.

[0027] Based on this, it can be known that during the operation of the switch tubes Q1 and Q2, the inductor current is closely related to the voltage stored in the parasitic capacitance of the switch tubes Q1 and Q2. Therefore, the soft switching of the switch tube can be achieved by monitoring the inductor current of the resonant inductor Lr.

[0028] In another embodiment, when the converter 10 is a Boost converter, Figure 2b As shown, the Boost converter includes a switch tube Q3 (freewheeling tube), a switch tube Q4 (power tube), a resonant inductor Lm and a capacitor C4. The switch tube Q3 and the switch tube Q4 are connected in series with each other, and the second end of the switch tube Q3 also receives the input voltage through the resonant inductor Lm. The capacitor C4 is connected to the first end of the switch tube Q3 and the second end of the switch tube Q4 respectively, and the control end of the switch tube Q3 and the control end of the switch tube Q4 are also connected to the controller 20. Among them, the working principle of the Boost converter is similar to that of the Buck converter, which will not be repeated here.

[0029] In some embodiments, see Figure 4 , Figure 4is a structural block diagram of a converter control circuit provided by an embodiment of the present invention, such as Figure 4 As shown, the converter control circuit 30 includes a sampling resistor R5, a driving module 31 and a trigger module 32; The sampling resistor R5 is connected to the driving module 31 and the trigger module 32 respectively. The sampling resistor R5 is also used to connect to the converter 10. The trigger module 32 is also connected to the controller 20. The driving module 31 is also used to connect to the freewheeling tube in the converter 10. The driving module 31 is also used to receive a pulse signal. The sampling resistor R5 responds to the change of the inductor current in the converter 10 and outputs a corresponding sampling voltage based on the changed inductor current; The trigger module 32 is used to receive the sampled voltage and output a trigger signal to the controller 20 at the moment when the sampled voltage is greater than a preset voltage, so that the controller 20 controls the action of the power tube 10 in the converter according to the trigger signal; The driving module 31 is used to receive the sampled voltage, and when the pulse signal is at the first level, determine whether the sampled voltage is greater than the preset voltage, so as to output an opening signal to the freewheeling tube in the converter 10 when the sampled voltage is greater than the preset voltage, thereby controlling the freewheeling tube in the converter 10 to be opened according to the opening signal; and When the sampling voltage is less than the preset voltage or the pulse signal is at the second level, a shutdown signal is output to the converter 10, so that the freewheeling tube in the converter 10 is turned off according to the shutdown signal.

[0030] It can be known that the converter control circuit 30 mainly detects the inductor current in the converter 10 in real time through the sampling resistor R5, so as to determine the on-off time of the switch tube Q1 and the switch tube Q2 based on the inductor current, thereby realizing the soft switching of the switch tube Q1 and the switch tube Q2.

[0031] Specifically, when the sampling resistor R5 detects the inductor current, it will output the corresponding sampling voltage to the driving module 31 and the triggering module 32 based on the inductor current. At the same time, the driving module 31 will also receive the pulse signal. At this time, if the pulse signal is at the first level, the driving module 31 will receive the sampling voltage and determine whether the sampling voltage is greater than the preset voltage. If the sampling voltage is greater than the preset voltage, the driving module 31 will output an on signal to the freewheeling tube (switch tube Q2) in the converter 10, so that the switch tube Q2 is turned on based on the on signal; and if the sampling voltage is less than the preset voltage, the driving module 31 will output a shutoff signal to the switch tube Q2 to control the switch tube Q2 to shut down. Among them, when the pulse signal is at the second level, regardless of whether the pulse signal is greater than the preset voltage, the driving module 31 will output a shutoff signal to the switch tube Q2, so that the switch tube Q2 maintains the off state.

[0032] It should be noted that if Figure 3 As shown, the level state of the pulse signal (PWM-GH) is determined according to the working state of the switch tube Q1. When the switch tube Q1 is in the disconnected state, the pulse signal is at the first level; and when the switch tube Q1 is in the on state, the pulse signal is at the second level.

[0033] When the trigger module 32 receives the sampled voltage, it will output a trigger signal to the controller 20 at the instant when the sampled voltage is greater than the preset voltage. After receiving the trigger signal, the controller 20 will control the switch tube Q1 to operate according to the trigger signal. The preset voltage is based on the preset value of the inductor current (I n-set ), that is, when the collected inductor current is greater than the preset value, it is considered that the sampled voltage is greater than the preset voltage, and vice versa.

[0034] In some embodiments, when the controller 20 controls the action of the switch tube Q1, it may control the action of the switch tube Q1 according to the trigger signal, or it may directly control the action of the switch tube Q1. If the controller 20 controls the switch tube Q1 to turn on according to the trigger signal, the controller 20 will monitor the inductor current of the resonant inductor Lr in real time, and directly control the switch tube Q1 to turn off after the inductor current meets the condition; if the controller 20 controls the switch tube Q1 to turn off according to the trigger signal, it will directly control the switch tube Q1 to turn on after the inductor current meets the condition. For example, when the switch tube Q1 is turned on based on the trigger signal, the inductor current of the resonant inductor Lr will increase linearly, such as Figure 3As shown, when the inductor current increases to the peak current of the inductor current (I pm ), the controller 20 will control the switch tube Q1 to turn off.

[0035] In another embodiment, the trigger signal is the moment when the first signal jumps to the second signal, and the trigger module 32 includes a first comparison unit 321 and a trigger unit 322; The first comparison unit 321 is connected to the trigger unit 322, the first comparison unit 321 and the trigger unit 322 are also connected to the sampling resistor R5, and the trigger unit 322 is also connected to the controller 20; The first comparison unit 321 is used to receive the sampled voltage, and output a first control signal to the trigger unit 322 when the sampled voltage is less than the preset voltage, so that the trigger unit 322 outputs a first signal to the controller 20 according to the first control signal; and When the sampled voltage is greater than the preset voltage, a second control signal is output to the trigger unit 322 , so that the trigger unit 322 outputs a second signal to the controller 20 according to the second control signal, thereby enabling the controller 20 to control the action of the power tube in the converter 10 .

[0036] It can be known that the inductor current on the resonant inductor Lr changes in real time as the switch tubes Q1 and Q2 are turned on and off. Therefore, when the converter 10 is working, the sampling voltage output by the sampling resistor R5 also changes in real time.

[0037] When the sampling resistor R5 outputs the sampling voltage to the trigger module 32, the first comparison unit 321 compares the sampling voltage with the preset voltage, and outputs a first control signal to the trigger unit 322 when the sampling voltage is less than the preset voltage; and if the sampling voltage is greater than the preset voltage, the first comparison unit 321 outputs a second control signal to the trigger unit 322. When the trigger unit 322 receives the first control signal, it compares the sampling voltage with the preset voltage according to the first control signal. At this time, since the sampling voltage is less than the preset voltage, the trigger unit 322 outputs a first signal to the controller 20 according to the first control signal. Among them, since the switch tube Q1 will only act at the moment of receiving the trigger signal (the first signal jumps to the second signal), the controller 20 will not control the switch tube Q1 to act at this time. When the trigger unit 322 receives the second control signal, the trigger unit 322 will output a second signal to the controller 20 based on the second control signal. At the moment of receiving the second signal, the controller 20 will output a trigger signal to the switch tube Q1, thereby controlling the action of the switch tube Q1.

[0038] It should be noted that, in this embodiment, the controller 20 is set to be falling edge triggered, that is, when the controller 20 receives a falling edge signal, it will control the switch tube Q1 to act. Based on this, the first signal is a high level signal, and the second signal is a low level signal. Optionally, in other embodiments, the controller 20 can also be rising edge triggered, that is, when the controller 20 receives a signal that jumps from a low level to a high level, it controls the switch tube Q1 to act.

[0039] Further, in some embodiments, see Figure 5 , Figure 5 is a circuit diagram of a converter control circuit provided by an embodiment of the present invention, such as Figure 5 As shown, the first comparison unit 321 includes a comparator U2, a resistor R15, a resistor R17, a capacitor C10 and a capacitor C11; the trigger unit 322 includes a resistor R19, a resistor R20, a resistor R13, a resistor R18, a switch tube Q5, a comparator U3, a capacitor C7 and a capacitor C8.

[0040] The non-inverting input terminal of the comparator U2 is connected to the sampling resistor R5 through the resistor R17, the non-inverting input terminal of the comparator U2 is also grounded through the capacitor C10, and the inverting input terminal of the comparator U2 is connected to the reference power supply (V RF2), the inverting input terminal of the comparator U2 is also grounded through the capacitor C11, and the output terminal of the comparator U2 is connected to the trigger unit 322.

[0041] The control end of the switch tube Q5 is connected to the first comparison unit 321 through the resistor R19, and the control end of the switch tube Q5 is also grounded through the resistor R20. The first end of the switch tube Q5 is connected to the non-inverting input end of the comparator U3, and the non-inverting input end of the comparator U3 is also connected to the reference power supply (V RF2 ), the non-inverting input terminal of the comparator U3 is also connected to the ground through the capacitor C8, the inverting input terminal of the comparator U3 is connected to the sampling resistor R5 through the resistor R18, the inverting input terminal of the comparator U3 is also connected to the ground through the capacitor C7, and the output terminal of the comparator U3 is connected to the controller 20.

[0042] Specifically, when the sampling resistor R5 outputs the sampling voltage, the in-phase input terminal of the comparator U2 receives the sampling voltage through the resistor R17, and compares the sampling voltage with the preset voltage corresponding to the reference power supply. At this time, if the sampling voltage is less than the preset voltage, the comparator U2 outputs a first control signal (a low-level signal). When the comparator U2 outputs the first control signal, the switch tube Q5 is cut off based on the first control signal, and the voltage at the in-phase input terminal of the comparator U3 is the preset voltage; at the same time, the inverting input terminal of the comparator U3 receives the sampling voltage through the resistor R18. Since the sampling voltage is less than the preset voltage at this time, the comparator U3 outputs a first signal (a high-level signal) to the controller 20.

[0043] When the sampled voltage is greater than the preset voltage, the comparator U2 will output a second control signal, and the switch tube Q5 will be turned on based on the second control signal, thereby pulling down the voltage of the non-inverting input terminal of the comparator U3, so that the comparator U3 outputs a second signal (low level signal) to the controller 20. When the controller 20 receives the second signal, it is considered that the controller 20 receives the trigger signal (GH-ON), and thus controls the switch tube Q1 to act according to the trigger signal, thereby realizing the soft switching of the switch tube Q1.

[0044] In yet another embodiment, Figure 4 As shown, the driving module 31 includes a first control unit 311, a second comparison unit 312 and a second control unit 313; The second comparison unit 312 is connected to the first control unit 311 and the second control unit 313 respectively, the second comparison unit 312 is also connected to the sampling resistor R5, the second control unit 313 is also connected to the freewheeling tube in the converter 10, and the first control unit 311 is also used to receive the pulse signal; The first control unit 311 is used to control the second comparison unit 312 to determine whether the sampling voltage is greater than a preset voltage when the pulse signal is at the first level, so that the second comparison unit 312 outputs a first drive signal to the second control unit 313 when the sampling voltage is greater than the preset voltage; and outputs a second drive signal to the second control unit 313 when the sampling voltage is less than the preset voltage; and When the pulse signal is at a second level, controlling the second comparison unit 312 to output a second driving signal to the second control unit 313; The second control unit 313 is used for outputting an opening signal to the freewheeling tube in the converter 10 when receiving the first driving signal, so that the freewheeling tube in the converter 10 is opened according to the opening signal; and When the second driving signal is received, a shutdown signal is output to the converter 10, so that the freewheeling tube in the converter 10 is turned off according to the shutdown signal.

[0045] Specifically, when the sampling resistor R5 outputs the sampling voltage to the driving module 31, the first control unit 311 receives the pulse signal, and when the pulse signal is at the first level, transmits the sampling voltage to the second comparison unit 312, so that the second comparison unit 312 determines the size of the sampling voltage and the preset voltage. When the sampling voltage is greater than the preset voltage, the first driving signal is output to the second control unit 313; and if the sampling voltage is less than the preset voltage, the second driving signal is output to the second control unit 313. If the pulse signal is at the second level, the first control unit 311 controls the second comparison unit 312 to directly output the second driving signal to the second control unit 313. When the second control unit 313 receives the first driving signal, it outputs an opening signal to the freewheeling tube in the converter 10 based on the first driving signal to control the freewheeling tube to be opened; and if the second control unit 313 receives the second driving signal, it controls the freewheeling tube to be closed according to the second driving signal.

[0046] In yet another embodiment, see Figure 5The first control unit 311 includes a resistor R25, a resistor R26 and a switch tube Q6; the second comparison unit 312 includes a comparator U4, a resistor R23 and a capacitor C14; the second control unit 313 includes a resistor R29, a resistor R30, a resistor R31, a resistor R32, a switch tube Q7, a switch tube Q8, a switch tube Q9 and a switch tube Q10.

[0047] The control end of the switch tube Q6 receives the pulse signal through the resistor R25, and the control end of the switch tube Q6 is also grounded through the resistor R26. The first end of the switch tube Q6 is respectively connected to the sampling resistor R5 and the second comparison unit 312, and the second end of the switch tube Q6 is used for grounding.

[0048] The non-inverting input terminal of the comparator U4 is connected to the sampling resistor R5 and the first control unit 311 respectively, and the inverting input terminal of the comparator U4 is connected to the reference power supply (V RF2 ), the inverting input terminal of the comparator U4 is also grounded through the capacitor C14, and the output terminal of the comparator U4 is connected to the second control unit 313.

[0049] The control end of the switch tube Q7 is connected to the second comparison unit 312, the first end of the switch tube Q7 is connected to the control end of the switch tube Q8 through the resistor R30, the control end of the switch tube Q8 is also connected to the first power supply (12V) through the resistor R29, the second end of the switch tube Q8 is respectively connected to the control ends of the switch tube Q9 and the switch tube Q10 through the resistor R31, the control end of the switch tube Q10 is also grounded through the resistor R32, the first end of the switch tube Q8 and the first end of the switch tube Q9 are both connected to the first power supply, and the second end of the switch tube Q9 and the first end of the switch tube Q10 are also both connected to the freewheeling tube in the converter 10.

[0050] Among them, Figure 5 It can be known that the switch tube Q7 and the switch tube Q9 are N-channel switch tubes, and the switch tube Q8 and the switch tube Q10 are P-channel switch tubes.

[0051] Specifically, when the pulse signal is at the first level (low level signal), the switch tube Q6 is in the cut-off state. At this time, the sampled voltage will be directly output to the non-inverting input terminal of the comparator U4, and the comparator U4 will compare the sampled voltage with the preset voltage corresponding to the reference power supply. If the sampled voltage is greater than the preset voltage, the comparator U4 will output a first drive signal (high level signal) to the switch tube Q7 to turn on the switch tube Q7. When the switch tube Q7 is turned on, the switch tubes Q8 and Q9 are also turned on, thereby outputting an on signal (high level) to the switch tube Q2, thereby controlling the soft on of the switch tube Q2.

[0052] If the sampling voltage is less than the preset voltage, the comparator U4 will output a second driving signal (low level signal), and the switch tube Q7 will be turned off after receiving the low level signal, thereby turning off the switch tubes Q8 and Q9. When the switch tube Q9 is turned off, the switch tube Q10 will be turned on, thereby outputting a shutdown signal (low level) to the switch tube Q2, thereby controlling the switch tube Q2 to be softly shut down.

[0053] When the pulse signal is at the second level (high level signal), the switch tube Q6 is turned on, so that the voltage at the in-phase input terminal of the comparator U4 is directly pulled down. At this time, the sampling voltage will be discharged through the switch tube Q6, and the comparator U4 will directly output the second drive signal, so that the switch tube Q2 is turned off.

[0054] In some embodiments, Figure 5 As shown, the second control unit 313 also includes a resistor R33, a resistor R34 and a diode D1; the resistor R33 is connected in series with the diode D1, and the series-connected resistor R33 and diode D1 are also connected in parallel with the resistor R34, and the resistor R34 is also respectively connected to the second end of the switch tube Q9 and the freewheeling tube in the converter 10. Specifically, when the switch tubes Q7, Q8, and Q9 are turned on, the voltage of the first power supply will form an on signal through the switch tube Q9 and the resistor R34 to act on the freewheeling tube, thereby controlling the freewheeling tube to be turned on. When the switch tube Q10 is turned on, the driving voltage on the freewheeling tube will be reversely input to the second control unit 313. At this time, the diode D1 is turned on, and the driving voltage will be quickly discharged through the resistor R33, the resistor R34, and the switch tube Q10, so that the freewheeling tube in the converter 10 is quickly turned off.

[0055] It should be noted that when the converter 10 is in a heavy load state, the peak value of the inductor current will be very large when the power tube in the converter 10 is turned off, so that the parasitic capacitor terminal voltage of the switch tube in the converter 10 will resonate to zero quickly; and if the converter 10 is in a light load state, the peak value of the inductor current of the resonant inductor Lr will be very small, so that the time for the parasitic capacitor to resonate to zero is longer. Therefore, during the operation of the converter 10, it is necessary to adjust the real-time switching time of the switch tube Q1 and the switch tube Q2 according to the inductor current, so that the switch tube Q1 or the switch tube Q2 is a soft switch when it is in operation. Based on this, the present application introduces a delay unit 314 to determine the time of the switch tube Q2 action based on the delay unit 314 and the inductor current, thereby reducing the loss of the converter 10.

[0056] Further, in another embodiment, if Figure 4 As shown, the driving module 31 further includes a delay unit 314, and the delay unit 314 is connected to the sampling resistor R5 and the second comparison unit 312 respectively; The delay unit 314 is used to obtain the sampled voltage, and based on the magnitude of the sampled voltage, delay the sampled voltage by a corresponding time and then input the sampled voltage to the second comparison unit 312 .

[0057] Specifically, after the sampling resistor R5 outputs the sampling voltage, the delay unit 314 receives the sampling voltage, and based on the magnitude of the sampling voltage, delays the sampling voltage by a preset time and then inputs it into the second comparison unit 312, so that the second comparison unit 312 determines the magnitude of the sampling voltage and the preset voltage. It should be noted that due to the influence of the load condition on the inductor current, the magnitude of the inductor current of the converter 10 is not the same at the same time, thereby affecting the delay time of the delay unit 314. Therefore, the delay time of the delay unit 314 is determined by the magnitude of the sampling voltage corresponding to the inductor current, thereby ensuring the soft switching of the switch tube in the converter 10.

[0058] In some embodiments, Figure 5 As shown, the delay unit 314 includes a resistor R24 ​​and a capacitor C13; the resistor R24 ​​is connected to the sampling resistor R5 and the capacitor C13 respectively, the first end of the capacitor C13 is connected to the second comparison unit 312, and the second end of the capacitor C13 is used for grounding.

[0059] When the sampling resistor R5 outputs the sampling voltage, the capacitor C13 receives the sampling voltage through the resistor R24 ​​and starts charging based on the sampling voltage; and after charging for a corresponding time, the capacitor C13 inputs the sampling voltage to the second comparison unit 312. Since the capacity of the capacitor C13 is fixed, the larger the sampling voltage, the faster the capacitor C13 is charged, and the faster the second comparison unit 312 receives the sampling voltage.

[0060] In some embodiments, Figure 4 As shown, the converter control circuit 30 further includes an amplifying module 33; the amplifying module 33 is respectively connected to the sampling resistor R5, the trigger module 32 and the driving module 31; The amplifying module 33 is used to receive the sampling voltage output by the sampling resistor R5 , and amplify the sampling voltage and output it to the triggering module 32 and the driving module 31 for connection.

[0061] Specifically, after the sampling resistor R5 outputs a sampling voltage based on the inductor current, the sampling voltage is input to the amplification module 33, so that the amplification module 33 amplifies the sampling voltage and inputs the amplified sampling voltage to the driving module 31 and the trigger module 32. It should be noted that, since the resistance value of the sampling resistor R5 is small, when the inductor current flows through the sampling resistor R5, the voltage drop across the sampling resistor R5 is also small. Therefore, in order to accurately obtain the current change of the resonant inductor Lr, the amplification module 33 is introduced, and the sampling voltage is amplified by the amplification module 33, thereby improving the switching accuracy of the converter 10.

[0062] In some embodiments, Figure 5 As shown, the amplification module 33 includes a differential amplifier U1 and a resistor R10; The two input terminals of the differential amplifier U1 are respectively connected to the two ends of the sampling resistor R5, and the non-inverting input terminal of the differential amplifier U1 is also used to connect to the first power supply V RF1 The output end of the differential amplifier U1 is connected to the driving module 31 and the trigger module 32 respectively, and the resistor R10 is connected to the output end of the differential amplifier U1 and the inverting input end of the differential amplifier U1 respectively.

[0063] The differential amplifier refers to a device that amplifies the difference between two input signals. Therefore, when current flows through the sampling resistor R5, a corresponding sampling voltage will be generated on the sampling resistor R5. At this time, the differential amplifier U1 will obtain the voltage drop (sampling voltage) on the sampling resistor R5, amplify the voltage drop, and finally input the amplified sampling voltage to the driving module 31 and the trigger module 32.

[0064] An embodiment of the present invention provides a converter control circuit, which includes a sampling resistor, a driving module and a trigger module; the sampling resistor is connected to the driving module and the trigger module respectively, the sampling resistor is also used to connect the converter, the trigger module is also connected to the controller, the driving module is also used to connect the freewheeling tube in the converter, and the driving module is also used to receive a pulse signal; the sampling resistor responds to the change of the inductor current in the converter, and outputs a corresponding sampling voltage based on the changed inductor current; the trigger module is used to receive the sampling voltage, and output a trigger signal to the instant when the sampling voltage is greater than a preset voltage. The controller is used to control the action of the power tube in the converter according to the trigger signal; the driving module is used to receive the sampling voltage, and when the pulse signal is at the first level, determine whether the sampling voltage is greater than the preset voltage, so as to output an on signal to the freewheeling tube in the converter when the sampling voltage is greater than the preset voltage, thereby controlling the freewheeling tube in the converter to be turned on according to the on signal; and when the sampling voltage is less than the preset voltage or the pulse signal is at the second level, output a shutoff signal to the converter, so that the freewheeling tube in the converter is turned off according to the shutoff signal. Based on this, the action time of the power tube and the freewheeling tube can be determined in real time according to the inductor current, so that the current corresponding to the freewheeling tube and the power tube when they are in action is consistent, thereby improving the stability and safety of the converter; and the action time of the power tube and the freewheeling tube is adjusted in real time according to the relationship between the load condition of the converter and the inductor current, thereby reducing the loss of the power tube and improving the conversion efficiency of the converter.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may also be combined, the steps may be implemented in any order, and there are many other changes in different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they may still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A converter control circuit, characterized in that: The converter control circuit includes a sampling resistor, a driving module and a trigger module; The sampling resistor is connected to the driving module and the triggering module respectively, the sampling resistor is also used to connect the converter, the triggering module is also connected to the controller, the driving module is also used to connect the freewheeling tube in the converter, and the driving module is also used to receive the pulse signal; The sampling resistor responds to the change of the inductor current in the converter and outputs a corresponding sampling voltage based on the changed inductor current; The trigger module is used to receive the sampled voltage and output a trigger signal to the controller at the moment when the sampled voltage is greater than a preset voltage, so that the controller controls the action of the power tube in the converter according to the trigger signal; The driving module is used to receive the sampled voltage, and when the pulse signal is at a first level, determine whether the sampled voltage is greater than the preset voltage, so as to output an opening signal to the freewheeling tube in the converter when the sampled voltage is greater than the preset voltage, thereby controlling the freewheeling tube in the converter to be opened according to the opening signal; as well as When the sampling voltage is less than the preset voltage or the pulse signal is at the second level, a shutdown signal is output to the converter, so that the freewheeling tube in the converter is shut down according to the shutdown signal.

2. The converter control circuit according to claim 1, characterized in that: The trigger signal is the moment when the first signal jumps to the second signal, and the trigger module includes a first comparison unit and a trigger unit; The first comparison unit is connected to the trigger unit, the first comparison unit and the trigger unit are also connected to the sampling resistor, and the trigger unit is also connected to the controller; The first comparison unit is used to receive the sampled voltage, and output a first control signal to the trigger unit when the sampled voltage is less than the preset voltage, so that the trigger unit outputs a first signal to the controller according to the first control signal; as well as When the sampled voltage is greater than the preset voltage, a second control signal is output to the trigger unit, so that the trigger unit outputs a second signal to the controller according to the second control signal, thereby enabling the controller to control the action of the power tube in the converter.

3. The converter control circuit according to claim 2, characterized in that: The first comparison unit includes a comparator U2, a resistor R15, a resistor R17, a capacitor C10 and a capacitor C11; The non-inverting input terminal of the comparator U2 is connected to the sampling resistor through the resistor R17, the non-inverting input terminal of the comparator U2 is also grounded through the capacitor C10, the inverting input terminal of the comparator U2 is connected to the reference power supply through the resistor R15, the inverting input terminal of the comparator U2 is also grounded through the capacitor C11, and the output terminal of the comparator U2 is connected to the trigger unit.

4. The converter control circuit according to claim 3, characterized in that: The trigger unit includes a resistor R19, a resistor R20, a resistor R13, a resistor R18, a switch tube Q5, a comparator U3, a capacitor C7 and a capacitor C8; The control end of the switch tube Q5 is connected to the first comparison unit through the resistor R19, and the control end of the switch tube Q5 is also grounded through the resistor R20. The first end of the switch tube Q5 is connected to the non-inverting input end of the comparator U3, and the non-inverting input end of the comparator U3 is also connected to the reference power supply through the resistor R13. The non-inverting input end of the comparator U3 is also grounded through the capacitor C8. The inverting input end of the comparator U3 is connected to the sampling resistor through the resistor R18, and the inverting input end of the comparator U3 is also grounded through the capacitor C7. The output end of the comparator U3 is connected to the controller.

5. The converter control circuit according to any one of claims 1 to 4, characterized in that: The driving module includes a first control unit, a second comparison unit and a second control unit; The second comparison unit is connected to the first control unit and the second control unit respectively, the second comparison unit is also connected to the sampling resistor, the second control unit is also connected to the freewheeling tube in the converter, and the first control unit is also used to receive the pulse signal; The first control unit is used to control the second comparison unit to determine whether the sampling voltage is greater than a preset voltage when the pulse signal is at a first level, so that the second comparison unit outputs a first drive signal to the second control unit when the sampling voltage is greater than the preset voltage; and outputs a second drive signal to the second control unit when the sampling voltage is less than the preset voltage; as well as When the pulse signal is at a second level, controlling the second comparing unit to output a second driving signal to the second controlling unit; The second control unit is used for outputting an opening signal to the freewheeling tube in the converter when receiving the first driving signal, so that the freewheeling tube in the converter is opened according to the opening signal; as well as When the second driving signal is received, a shutdown signal is output to the converter, so that the freewheeling tube in the converter is turned off according to the shutdown signal.

6. The converter control circuit according to claim 5, characterized in that: The second comparison unit includes a comparator U4, a resistor R23 and a capacitor C14; The non-inverting input terminal of the comparator U4 is connected to the sampling resistor and the first control unit respectively, the inverting input terminal of the comparator U4 is connected to the reference power supply through the resistor R23, the inverting input terminal of the comparator U4 is also grounded through the capacitor C14, and the output terminal of the comparator U4 is connected to the second control unit.

7. The converter control circuit according to claim 5, characterized in that: The driving module also includes a delay unit; The delay unit is connected to the sampling resistor and the second comparison unit respectively; The delay unit is used to obtain the sampled voltage, and based on the magnitude of the sampled voltage, delay the sampled voltage by a corresponding time and then input it into the second comparison unit.

8. The converter control circuit according to claim 5, characterized in that: The second control unit includes a resistor R29, a resistor R30, a resistor R31, a resistor R32, a switch tube Q7, a switch tube Q8, a switch tube Q9 and a switch tube Q10; The control end of the switch tube Q7 is connected to the second comparison unit, the first end of the switch tube Q7 is connected to the control end of the switch tube Q8 through the resistor R30, the control end of the switch tube Q8 is also connected to the first power supply through the resistor R29, the second end of the switch tube Q8 is respectively connected to the control ends of the switch tube Q9 and the switch tube Q10 through the resistor R31, the control end of the switch tube Q10 is also grounded through the resistor R32, the first end of the switch tube Q8 and the first end of the switch tube Q9 are both connected to the first power supply, and the second end of the switch tube Q9 and the first end of the switch tube Q10 are also both connected to the freewheeling tube in the converter.

9. The converter control circuit according to any one of claims 1 to 4, characterized in that: The converter control circuit also includes an amplification module; The amplification module is respectively connected to the sampling resistor, the trigger module and the driving module; The amplifying module is used for receiving the sampling voltage output by the sampling resistor, and amplifying the sampling voltage and then outputting it to the triggering module and the driving module.

10. A conversion system, characterized in that: The transformation system comprises: Converter; Controller; and A converter control circuit as claimed in any one of claims 1 to 9.

Images